This application claims the benefit of Korean Application No. 99-10952, filed Mar. 30, 1999, in the Korean Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an apparatus for discriminating an optical disc and a method therefor, and more particularly, to an optical disc discrimination apparatus and method for discriminating an optical disc by using a size of an envelope of a radio frequency (RF) signal read from the optical disc at a state where only a focusing operation has been performed, to thereby discriminate the type of the optical disc accurately and conveniently.
2. Description of the Related Art
A digital versatile disc (DVD) can record a large amount of information and provide a high picture quality in comparison with a compact disc (CD). As a result, a DVD has come into the spotlight as a storage medium of the next generation. A recent form of the DVD is a DVD-RAM which provides functions of recording, deletion, and rewriting data on a medium, such as those of a RW (rewrite) disc. A DVD-RAM drive apparatus reproducing the DVD-RAM includes an optical pickup compatible with a DVD and a CD so that signals recorded on a DVD-ROM as well as the DVD-RAM and the CD having a relatively large track pitch, can be reproduced. Track structures of the discs which can be reproduced from the DVD-RAM drive apparatus are shown in FIGS. 1A through 1C.
FIGS. 1A through 1C show the track structures of a CD, a DVD-ROM and a DVD-RAM, respectively. In the CD of FIG. 1A and the DVD-ROM of FIG. 1B, a pit is engraved to a depth of approximately 0.1 in a helical fashion from the center of the disc on a single mirror plane. Here, a track pitch is about 1.6 xcexcm in the case of a CD and about 0.74 xcexcm in case of a DVD-ROM. The DVD-RAM of FIG. 1C is configured as a land/groove track structure having a difference of about 6/xcexc in depth. Data can he recorded on both the land and the groove. Since a recording method of the DVD-RAM adopts a change in phase, a data pit region does not have a physical depth as a CD or a DVD-ROM.
An optical disc reproduction apparatus which can reproduce a CD, a DVD-ROM and a DVD-RAM having respectively different track structure as described above should discriminate whether a loaded disc is a DVD-RAM, a DVD-ROM or a CD prior to reproducing a signal from the loaded disc.
Thus, it is an object of the present invention to provide an optical disc discrimination apparatus and method for discriminating a type of a disc according to a difference in amplitude of an envelope waveform of a radio frequency (RF) signal read from the disc at a state where only a focusing operation is performed.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To accomplish the above and other objects of the present invention, there is provided an optical disc discrimination apparatus for use in an optical disc reproducer which can reproduce a plurality of different types of discs with only a single optical pickup, the optical disc discrimination apparatus comprising: an RF envelope generator which detects an envelope signal from an RF signal read from a loaded one of the discs; and a controller which detects an amplitude of the envelope signal detected by the RF envelope generator at an off-track state, and which discriminates the type of the disc using the detected amplitude.
There is also provided an optical disc discrimination method of discriminating a type of a disc for use in an optical disc reproducer which can reproduce a plurality of different types of discs with only a single optical pickup, the optical disc discrimination method comprising: (a) obtaining an envelope signal from an RF signal detected from a loaded one of discs at an off-track state of the disc; (b) detecting an amplitude of the envelope signal obtained in the step (a); (c) comparing the amplitude of the envelope signal detected in the step (b) with a predetermined reference level; and (d) discriminating whether the disc is a CD, a DVD-ROM, or a DVD-RAM based on the comparison result of the step (c).